Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 10 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

MODERATE avalanche danger will exist this morning and continue through the afternoon hours for all elevations and aspects on slope 35 degrees and steeper due to loose wet avalanche problems. Cloud cover last night is expected to have kept overnight snow surface refreeze from occurring in many areas. A period of LOW avalanche danger with supportable snow surface conditions may not exist this morning. A possible wet slab avalanche occurred yesterday in the Mount Rose area. Details are limited.

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2

    Air temperatures were in the mid 30s to upper 40s last night in the 6,500' to 9,500' elevation range. Cloud cover is expected to have inhibited or greatly reduced the amount of snow surface refreeze that usually occurs from radiational cooling. As a result, a poor overnight snow surface refreeze is expected to have occurred last night in many areas. In areas where some amount of snow surface refreeze did occur it may be deceptively superficial, turning unsupportable and potentially unstable prior to the mid morning hours.

    Areas that did not refreeze will be easy to identify this morning. In areas where some amount of snow surface refreeze did occur, kick boots through the surface crust to assess thickness. Beware of areas of crust less than 3 inches thick. In direct sun exposed areas that thickness of crust will provide only a very short window of supportable conditions before melting away and exposing deeper wet snow below and potential loose wet avalanche problems.

Avalanche Discussion

A report was received yesterday evening of a potential wet slab avalanche that occurred around 2 pm on the Fireplug, aka The Diamond feature adjacent to the Mount Rose Highway. Details are limited at this time and more will be known after a visit to the site today. The slope where the avalanche occurred is a SE aspect near treeline. The avalanche started at around 9,000' and ran for about 300 vertical feet. The avalanche was large enough to bury or injure a person.

Observations made yesterday on the north side of Carson Pass on the SW flanks of Red Lake Peak revealed that a decent snow surface refreeze had occurred Saturday night in open areas and a poor refreeze had occurred in treed areas. Snow surface conditions in open areas remained supportable through the morning hours with the first signs of the transition to unsupportable wet snow observed on a S aspect at 8,700' at 11:15 am. The high sun angle of April was noted to allow for surface melt-freeze conditions to occur on steep N-NE aspect terrain at 9,600'.  

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